CADD technician Rebekah S. Wolf shares a tip about an AutoCAD system variable that manages how the Offset command handles vertices of polylines that it creates.

"Sometimes I have to offset a stream or wetlands line in order to create a buffer. If I were to do a regular offset, then I would need to go through and fillet all of the corners in order to create a buffer that is an exact distance from the original line at all points perpendicular to the offset. To streamline the process, I temporarily change the OFFSETGAPTYPE system variable: 0 is a regular offset, 1 is an offset with fillet, and 2 is an offset with chamfer."

Notes from Cadalyst Tip Reviewer Brian Benton: When a "regular" offset is created from a polyline, the new polyline is parallel, with all corners trimmed at each other's intersection point. In the examples given by the tipster, however, that's not what she wants to create; she needs an offset that is even equidistant from the vertices as well. Setting OFFSETGAPTYPE to 1 will create a fillet at the new object's vertices with a radius equal to the offset distance. In the example image below, I offset the blue line by 5 units. The red line was created and has a radius of 5 at the new vertex. The vertex on the red line at the right could not have a radius of 5 units applied, as the line would no longer be 5 units away from the source line.

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Comment by Krupa,Ken

Posted on 2012-06-19 19:25:08

Did not know there was such a thing - thanks!

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